Object having a microbicide coating, method for the production thereof and use of the same

ABSTRACT

A microbicidally coated article, especially a container, having on at least part of it a coating comprising an organically modified inorganic matrix comprising silver colloids which is obtainable by application of a coating composition comprising a) a hydrolysate or condensate based on at least one hydrolysable silane with at least one non-hydrolysable substituent and b) a silver compound to the surface of the article and treatment with heat and/or radiation to form the silver colloid coating. Articles coated in accordance with the invention are therefore particularly suitable for purposes of disinfection, preservation, cosmetic, pharmaceutical or medical purposes. Articles from the pharmaceutical or medical sector, especially containers for pharmaceuticals or articles or components which come into contact with the human body and are required to be free from germs, are preferred fields of application.

[0001] The present invention relates to microbicidally coated articles,especially containers, whose coating comprises an organically modifiedinorganic matrix comprising silver colloids, to a method of producingthem and to their use for disinfection, preservation or medicalpurposes.

[0002] It is known that silver ions exert a strongly microbicidaleffect. The microbicidal effect of the silver ions is also evident whensilver compounds are present in a matrix, for example a polymer matrixhaving a sufficiently free volume, and even when silver colloids havebeen bound into a matrix. Silver ions must diffuse at a sufficient rateto the surface. To give microbicidal coatings, the silver can be used,for example, in the form of soluble compounds in paint solutions or inthe form of silver colloid solutions.

[0003] Soluble silver compounds generally have the disadvantage thattheir diffusion is relatively rapid and their effect is exhaustedrelatively quickly, especially when in contact with solutions. Toproduce silver colloid coating compositions, the silver colloids can bemixed into a coating composition. This has the general disadvantage,however, that stable silver colloid solutions are required, whosestability must generally be brought about by electrostatic stabilization(pH stabilization); in other words, protic solvents are needed and it isnecessary to set defined pH levels, with the consequence that, for manycoating systems, the addition of silver colloids is not possible.

[0004] In another method, in a coating composition comprisingglass-forming elements, silver colloids are generated in situ fromsilver compounds during the coating process, giving coatings comprisingsilver colloids in a glass matrix. A disadvantage of this method,however, is that the coatings formed are brittle and that very hightemperatures are needed for the formation of the colloid-containingglass matrix. This method is therefore not suitable for the coating oftemperature-sensitive articles.

[0005] An object of the present invention is to provide eventemperature-sensitive articles with a silver colloid coating, wheresilver colloids generated in situ can be prepared even at relatively lowtemperatures and where the curing of the coating can also take place atrelatively low temperatures. At the same time, relatively large colloidsshould be possible, since such colloids have high long-term activity.Moreover, a coating of high elasticity should be possible which can beemployed even on articles having a flexible surface.

[0006] These requirements are surprisingly met by the microbicidallycoated article, in particular a container, according to the presentinvention, there being present on at least part of the article a coatingcomprising an organically modified inorganic matrix comprising silvercolloids which is obtainable by application of a coating compositioncomprising a) a hydrolysate or condensate based on at least onehydrolysable silane with at least one non-hydrolysable substituent andb) a silver compound to the surface of the article and treatment withheat and/or radiation to form the silver colloid coating.

[0007] The present invention additionally provides a method of producinga microbicidally coated article comprising an organically modifiedinorganic matrix comprising a silver colloid coating, wherein a coatingcomposition comprising a) a hydrolysate or condensate based on at leastone hydrolysable silane with at least one non-hydrolysable substituentand b) a silver compound is applied to at least part of the surface ofthe article and is treated with heat and/or radiation to form the silvercolloid coating.

[0008] In accordance with the invention it is possible to obtain silvercolloid coatings at low temperatures, so that they are suitable fortemperature-sensitive articles. High elasticity of the coat allows thecoating of flexible articles. The articles coated in accordance with theinvention are distinguished by a strongly microbicidal effect.

[0009] The article to be coated may comprise any desired article. Onaccount of the microbicidal activity, the articles coated in accordancewith the invention are especially suitable for disinfection,preservation, cosmetic, pharmaceutical and/or medical purposes. Forarticles in the pharmaceutical or medical sector, for example for coatedcontainers for pharmaceuticals or for articles or components which areintended to come into contact with the human body and remain germ-free,the present invention is particularly suitable.

[0010] Preferably, therefore, the article in question is an article forthe keeping of solid (e.g. ointment-like), liquid or gaseous media,particularly for keeping liquid media, for example solutions. Thecontainers may comprise, for example, bottles, vials, ampoules,(sealable) pouches, packaging forms, such as blisters, tins, spraybottles or spray cans and tubes. The media for keeping are, inparticular, pharmaceuticals, preferably in liquid form, as solutions forexample, or other media used in the medical sector, for example isotonicsaline solutions and preservation or cleaning media for contact lenses.Containers for nasal sprays and eye drops are particularly preferred.Naturally, the containers may also be used in other fields.

[0011] Further preferred articles which are coated in accordance withthe invention are articles or instruments or parts thereof used in themedical sector, for example surgical instruments, trays and tubing.

[0012] All or part of the article may be coated. For example, it may beappropriate to coat only the inside surfaces of containers such aspharmaceutical vials, while the outer surface remains uncoated. Thearticle may be composed of one or more materials; for example, differentcomponents of the article may be composed of different materials.

[0013] The article to be coated or the part of the article that iscoated (substrate) may be of any desired material, for example of metalglass, ceramic, glass-ceramic, plastic or paper. Since one particularadvantage of the present invention is that it is possible to obtainsilver colloid coatings without having to employ high temperatures, theinvention is particularly suitable for heat-sensitive articles. It istherefore preferred to use articles or parts of articles made ofplastic. Examples of plastics are polyethylene, polypropylene,polyacrylate, such as polymethyl methacrylate and polymethyl acrylate,polyvinylbutyral polycarbonate, polyurethanes, ABS copolymers orpolyvinyl chloride, particular preference being given to polyethylene.The article may be conventionally pretreated in order, for example, tobring about cleaning, degreasing or better adhesion to the coating. Itis of course possible for the part of the article that is to be coated,as the substrate, to be coated separately first and then assembled toform the finished article.

[0014] The coating composition used comprises a) a hydrolysate orcondensate based on at least one hydrolysable silane with at least onenon-hydrolysable (carbon-containing) substituent and b) a silvercompound. The hydrolysate or condensate is preferably obtained bypartial hydrolysis or condensation of one or more silanes of the generalformula (I)

R_(a)SiX_((4-a))  (I)

[0015] in which the radicals R are identical or different and representnon-hydrolysable groups, the radicals X are identical or different anddenote hydrolysable groups or hydroxyl groups and a has the value 1, 2or 3, a value of 1 being preferred.

[0016] In the organosilanes of the formula (I) the hydrolysable groups Xare, for example, hydrogen or halogen (F, Cl, Br or I, especially Cl andBr), alkoxy (preferably C₁₋₆ alkoxy, especially C₁₋₄ alkoxy, such asmethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxyand tert-butoxy), aryloxy preferably C₆₋₁₀ aryloxy, such as phenoxy),acyloxy (preferably C₁₋₆ acyloxy, such as acetoxy or propionyloxy),alkylcarbonyl (preferably C₂₋₇ alkylcarbonyl, such as acetyl), amino,monoalkylamino or dialkylamino, the alkyl groups having preferably 1 to12, in particular 1 to 6, carbon atoms. Preferred hydrolysable radicalsare halogen, alkoxy groups and acyloxy groups. Particularly preferredhydrolysable radicals are alkoxy groups, especially methoxy and ethoxy.

[0017] R is a non-hydrolysable organic radical which may whereappropriate carry a functional group. Examples of R are alkyl(preferably C₁₋₆ alkyl, such as methyl, ethyl, n-propyl, isopropyl,n-butyl, sec-butyl and tert-butyl, pentyl, hexyl or cyclohexyl), alkenyl(preferably C₂₋₆ alkenyl, such as vinyl, 1-propenyl, 2-propenyl andbutenyl), alkynyl (preferably C₂₋₆ alkynyl, such as acetylenyl andpropargyl) and aryl (preferably C₆₋₁₀ aryl, such as phenyl andnaphthyl).

[0018] Specific examples of functional groups of the radical R, inaddition to the aforementioned groups containing unsaturated C—C bonds,are the epoxy, hydroxyl, ether, amino, monoalkylamino, diaylkamino, forexample with the above-defined C₁₋₆ alkyl groups, amide, carboxyl,mercapto, thioethet, vinyl, isocyanate, acryloyloxy, methacryloyloxy,acid anhydride, acid halide, cyano, halogen, aldehyde, alkylcarbonyl,sulfonic acid and phosphoric acid group. These functional groups areattached to the silicon atom via alkylene, alkenylene or arylene bridgegroups, which may be interrupted by oxygen or sulfur atoms or by —NH—groups. These bridge groups are derived, for example, from theabovementioned alkyl, alkenyl or aryl radicals. The radicals R containpreferably 1 to 18, especially 1 to 8, carbon atoms. The stated radicalsR and X may where appropriate have one or more customary substituents,such as halogen or alkoxy.

[0019] At least one of the hydrolysable silanes used having at least onenon-hydrolysable substituent preferably contains one of theabovementioned functional groups on the non-hydrolysable substituent. Byway of this functional group it is then possible for organiccrosslinking to take place, for example by reaction of the functionalgroups on the silanes with one another, in which case different or thesame functional groups may react with one another, or with functionalgroups on the organic compounds described below, which may likewise bepresent in the coating composition.

[0020] Preferred functional groups are the epoxide, acid anhydride andamino group, particular preference being given to a combination of atleast one hydrolysable silane having one or more epoxide groups on atleast one non-hydrolysable substituent and of at least one hydrolysablesilane having one or more amino groups on at least one non-hydrolysablesubstituent. An especially preferred combination is one furthercomprising, in addition to an epoxysilane and an aminosilane, at leastone hydrolysable silane having one or more acid anhydride groups on atleast one non-hydrolysable substituent.

[0021] In the preferred epoxysilanes of the above general formula (I) ahas a value of 1, X is preferably C₁₋₄ alkoxy, with particularpreference methoxy and ethoxy, and R is a non-hydrolysable radicalhaving at least one epoxide group, for example an aliphatic,cycloaliphatic or aromatic radical especially alkylene, for exampleC₁-C₆ alkylene, such as methylene, ethylene, propylene and butylene,having at least one epoxide group. The radical R is preferably aglycidyloxy-(C₁₋₆)-alkylene radical. Specific examples areβ-glycidyloxyethyl γ-glycidyloxypropyl δ-glycidyloxybutylε-glycidyloxypentyl ω-glycidyloxyhexyl and 2-(3,4-epoxycyclohexyl)ethyl.Epoxysilanes used with particular preference areγ-glycidyloxypropyltrimethoxysilane (GPTS) andγ-glycidyloxypropyltriethoxysilane (GPTES).

[0022] Preferred aminosilanes are those of the above general formula (I)in which a has a value of 1, X is preferably C₁₋₄ alkoxy, withparticular preference methoxy and ethoxy, and R is a non-hydrolysableradical having at least one amino group, for example an aliphatic,cycloaliphatic or aromatic radical, especially alkylene, for exampleC₁-C₆ alkylene, such as methylene, ethylene, propylene and butylene,having at least one primary, secondary or tertiary amino group. Forexample, R is an R¹ ₂N-(alkylene-NR¹)_(x)-alkylene radical in which x is0 to 5, the alkylene groups may be identical or different and may inparticular be those mentioned above, and R¹ is identical or different ateach occurrence and is hydrogen or an optionally substituted alkylradical for example those specified in general formula (I) above. R¹ mayalso be a divalent radical, for example alkylene, with the formation ofa heterocyclic ring. Where appropriate it is also possible for a furthernon-hydrolysable radical for example alkyl to be present (a=2). Specificexamples of such silanes are 3-aminopropyltrimethoxysilane (APTS),3-aminopropyltriethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,N-[N′-(2′-aminoethyl)-2-aminoethyl]-3-aminopropyltrimethoxysilane,N-[3-(triethoxysilyl)propyl]-4,5-dihydroidazole and[N-(2-aminoethyl)-3-aminopropyl]methyldiethoxysilane.

[0023] 3-Aminopropyltrimethoxysilane (APTS) is particularly preferred.

[0024] Preferred anhydridosilanes are those of the above general formula(I) in which a has a value of 1, X is preferably C₁₋₄ alkoxy, withparticular preference methoxy and ethoxy, and R is a non-hydrolysableradical having at least one anhydride group, for example an aliphatic,cycloaliphatic or aromatic radical, especially alkylene, for exampleC₁-C₆ alkylene, especially C₁-C₄ alkylene, such as methylene, ethylene,propylene and butylene, having an anhydride group. The anhydride group,which like the epoxide group is capable of condensation with aminogroups, may comprise, for example, radicals derived from carboxylicanhydrides, such as succinic anhydride, maleic anhydride or phthalicanhydride, which are connected to the silicon atom via one of theabovementioned radicals, especially C₁-C₄ alkylene. Examples are[3-(triethoxysilyl)propyl]succinic anhydride(dihydro-3-[3-(triethoxysilyl)propyl]-2,5-furandione, GF20) and[3-(trimethoxysilyl)propyl]succinic anhydride.

[0025] Where appropriate it is also possible to use hydrolysable silanesor precondensates thereof containing at least in part organic radicalssubstituted by fluorine. For this purpose it is possible, for example,to use hydrolysable silicon compounds of the general formula (I) havingat least one non-hydrolysable radical R which has, for example, onaverage from 2 to 30 fluorine atoms attached to carbon atoms which arepreferably separated from Si by at least two atoms. Hydrolysable groupswhich can be used in this context include for example those indicatedfor X in formula (I). Specific examples of fluorosilanes areC₂F₅—CH₂CH₂—SiZ₃, n-C₆F₁₃—CH₂CH₂—SiZ₃, n-C₈F₁₇—CH₂CH₂—SiZ₃, andn-C₁₀F₂₁—CH₂CH₂—SiZ₃, where Z=OCH₃, OC₂H₅ or Cl,iso-C₃F₇O—CH₂CH₂CH₂—SiCl₂(CH₃), n-C₆F₁₃—CH₂CH₂—SiCl₂(CH₃) andn-C₆F₁₃—CH₂CH₂—SiCl(CH₃)₂. The use of a fluorinated silane of this kindresults in hydrophobic and oleophobic properties being givenadditionally to the coating in question. Silanes of this kind aredescribed in detail in DE 4118184. The fraction of fluorinated silanesis preferably not more than 0.5 to 2% by weight based on the totalorganically modified inorganic polycondensate used.

[0026] Of the hydrolysable silanes having at least one non-hydrolysablesubstituent which are used for the hydrolysate or condensate, preferablyat least 40 mol %, more preferably at least 70 mol %, with particularpreference at least 90 mol %, have at least one functional group on atleast one non-hydrolysable substituent. In one preferred embodiment allof the hydrolysable silanes having at least one non-hydrolysablesubstituent that are used possess at least one functional group on atleast one non-hydrolysable substituent. In the case of the combined useof epoxysilane, aminosilane and anhydridosilane, theepoxysilane/aminosilane/anhydridosilane ratio is preferably 0.5 to 1.5/1to 3/1 to 3, based on the functional groups.

[0027] For the preparation of the hydrolysate or condensate it ispossible where appropriate to use further hydrolysable compounds of anelement M as matrix formers. These are, in particular, compounds of atleast one element M from main groups III to V and/or transition groupsII to IV of the Periodic Table of the Elements. They are preferablyhydrolysable compounds of Si, Al, B, Sn, Ti, Zr, V or Zn, especiallythose of Si, Al, Ti or Zr, or mixtures of two or more of these elements.It should be noted that, of course, other hydrolysable compounds mayalso be used, particularly those of elements from main groups I and IIof the Periodic Table (e.g. Na, K, Ca and Mg) and from transition groupsV to VIII of the Periodic Table (e.g. Mn, Cr, Fe and Ni). Hydrolysablecompounds of the lanthanides may also be used. These hydrolysablematrix-forming compounds without non-hydrolysable groups have inparticular the general formula MX_(b) (formula (II), where M is asdefined above, X is as defined above for formula (I) and b correspondsto the valence of the element M (e.g. SiX₄, AlX₃). The compounds mayalso be used in the form of prehydrolysates or precondensates.

[0028] Preferably, however, the latter compounds account for not morethan 20 mol %, in particular not more than 10 mol %, of the total amountof hydrolysable monomeric compounds employed. With particularpreference, not more than 4 mol %, or 0 mol %, of the total hydrolysablemonomeric compounds employed have no non-hydrolysable substituent.

[0029] The coating composition further comprises at least one silvercompound. This may comprise silver compounds soluble in water or organicsolvents, such as AgNO₃, though preferably the silver ions are used inthe form of complex compounds. The complexing agents are with particularpreference chelating agents, i.e. bidentate or multidentate ligands, forexample bidentate to hexadentate complexing agents. The solvent-solublesilver compound is therefore in particular a complex of silver ions withcomplexing agents, especially chelating agents. Silver complex compoundsof this kind are formed, for example, by adding a silver compound andcomplexing agent to a solvent, and the silver complex formed is thenused in the form of this solution for the coating composition.

[0030] The silver(I) ions and/or the silver complex compounds may reactunder reducing conditions to give metal colloids. Examples of complexingagents which form a silver complex compound with silver(I) ions arehalide ions, such as iodide, bromide and especially chloride (or thecorresponding hydrohalic acids), thio compounds, thiocyano compounds,sugars, such as pentoses and hexoses, for example glucose, β-dicarbonylcompounds, such as diketones, for example acetylacetonates, keto esters,for example acetoacetates and allyl acetoacetate, ether alcohols,carboxylic acids, carboxylates, for example acetate, citrate orglycolate, betaines, diols, polyols, including polymeric polyols such aspolyalkylene glycols, crown ethers, phosphorus compounds, mercaptocompounds, such as 3-mercaptopropyltrimethoxysilane and3-mercaptopropyltriethoxysilane, and amino compounds. Particularlypreferred complexing agents used are mercapto compounds, such asmercaptosilanes, amino compounds, such as aminosilanes, mono-, di-, tri-and tetraamines and higher polyamines. Examples of organic amines aretriethylenetetramine, diethylenetetramine, diethylenetriamine andethylenediamine. Examples of aminosilaxes are3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and, inparticular, 2-aminoethyl-3-aminopropyltrimethoxysilane (DIAMO),2-aminoethyl-3-aminopropyltriethoxysilane,aminohexyl-3-aminopropyltrimethoxysilane andaminohexyl-3-aminopropyltriethoxysilane. It is preferred to use silverdiamine complex compounds, with particular suitability being possessedby complexing agents containing at least two amino groups which are ableto form chelate complexes. Of the amino complexing agents, theaminosilanes are particularly preferred.

[0031] The complexing agents are advantageously incorporated into thematrix as it forms, especially firstly in the form of a weak coordinatedbond to Ag⁰ as it forms and then preferably in the form of a surfacemodification of the silver colloids formed, which can lead to thestabilization of the silver colloids in the matrix. The surfacemodification brought about by the complexing agent results in enhancedcompatibility between matrix and surface-modified silver colloid. Thecomplexing agents preferably also contain functional or non-functionalgroups which additionally promote the compatibility of the silvercolloids with the matrix. These may be, for example, polar groups (e.g.hydroxyl, amino or carboxyl groups), which promote compatibility withhydrophilic matrices or with the corresponding binder, or apolar groups(e.g. alkyl groups or aryl groups), which promote compatibility withhydrophobic matrices or with the corresponding binder.

[0032] Complexing is presumed to be accompanied by partial stabilizationof the silver ions, so that no spontaneous or daylight-induced reductiontakes place. Surprisingly, following reduction to Ag, accomplished forinstance by heat treatment or UV irradiation with oxidation of organiccompounds present, the Ag⁰ is highly mobile despite the surroundingcomplexing agents, and consequently it is possible for colloids to form,made up of several thousand atoms, for example.

[0033] When a complexing agent is used the ratio of Ag to complexinggroups present is preferably from 1:0.1 to 1:500, in particular from 1:1to 1:200. A bidentate complexing agent, for example, has two complexinggroups. The complexing agents may also function at least in part asreducing agents for the silver ions. Further suitable reducing agentsmay be the solvents described below, for example alcohols or ketones,the by-products formed during hydrolysis and condensation, for examplealcohols, the hydrolysable compounds employed, or a combination ofthese.

[0034] Where appropriate, the coating composition may also comprisenanoscale inorganic particulate solids. This gives the coating improvedmechanical strength (scratch resistance, hardness). Such solidsgenerally possess a particle size in the range from 1 to 300 nm or from1 to 100 nm, preferably from 2 to 50 nm and with particular preferencefrom 5 to 20 nm. This material may be used in the form of a powder butis preferably used in the form of a stabilized sol, especially anacidically or alkalinically stabilized sol. The nanoscale inorganicparticulate solids may be composed of any desired inorganic materialsbut are composed in particular of metals or metal compounds such as, forexample, (unhydrated or hydrated) oxides such as ZnO, CdO, SiO₂, TiO₂,ZrO₂, CeO₂, SnO₂, Al₂O₃, In₂O₃, La₂O₃, Fe₂O₃, Cu₂O, Ta₂O₅, Nb₂O₅, V₂O₅,MoO₃ or WO₃, chalcogenides, nitrides, phosphides, phosphates, silicates,zirconates, aluminates or carbides. The nanoscale inorganic particulatesolids preferably comprise an oxide, oxide hydrate, nitride or carbideof Si, Al, B, Zn, Cd, Ti, Zr, Ce, Sn, In, La, Fe, Cu, Ta, Nb, V, Mo orW, with particular preference of Si, Al, B, Ti and Zr. It isparticularly preferred to use oxides or oxide hydrates. Preferrednanoscale inorganic particulate solids are SiO₂, Al₂O₃, ITO, ATO, AlOOH,ZrO₂ and TiO₂. Examples of nanoscale SiO₂ particles are commercialsilica products, for example silica sols, such as the Levasils®, silicasols from Bayer AG, or pyrogenic silicas, for example the Aerosilproducts from Degussa.

[0035] The nanoscale inorganic particulate solids may be modified withorganic surface groups. The surface modification of nanoscaleparticulate solids is a method known in the state of the art, and isdescribed, for example, in WO 93/21127 (DE 4212633) and WO 98/51747 (DE19746885).

[0036] The coating composition may comprise further additives which inthe art are normally added according to intended purpose and desiredproperties. Specific examples are organic compounds, crosslinkingagents, solvents, organic and inorganic color pigments, dyes, UVabsorbers, lubricants, leveling agents, wetting agents, adhesionpromoters and initiators. The initiator may serve for thermally orphotochemically induced crosslinking.

[0037] Where appropriate it is possible for organic compounds orcrosslinking agents to be added to the coating composition. These may beorganic monomers, oligomers or polymers which in particular contain atleast two functional groups which are able to react with the functionalgroups of the hydrolysable silanes used, with the formation of anorganic crosslink. Examples of the compounds involved include aliphatic,cycloaliphatic and aromatic compounds. Preference is given to usingorganic compounds having at least two epoxide groups or at least twoamino groups. The use of the organic compounds may be advantageous, forexample, on price grounds. The organic compound is used in particular inan amount of not more than 30% by weight

[0038] Organic epoxide compounds that can be used may be derived, forexample, from aliphatic, cycloaliphatic or aromatic esters or ethers ormixtures thereof, based for example on ethylene glycol 1,4-butanediolpropylene glycol 1,6-hexanediol cyclohexanedimethanol, pentaerythritol,bisphenol A, bisphenol F or glycerol. Specific examples of organiccompounds having at least two epoxide groups are3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,bis(3,4-epoxycyclohexyl) adipate, 1,4-butanediol diglycidyl ether,cyclohexanedimethanol diglycidyl ether, glycerol triglycidyl ether,neopentyl glycol diglycidyl ether, pentaerytdritol polyglycidyl ether,2-ethylhexyl glycidyl ether, 1,6-hexanediol diglycidyl ether, propyleneglycol diglycidyl ether, polypropylene glycol diglycidyl ether,bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, epoxy resinsbased on bisphenol A, epoxy resins based on bisphenol F and epoxy resinsbased on bisphenol A/F. Specific examples of organic compounds having atleast two amino groups are 1,3-diaminopentane,1,5-diamino-2-methylpentane, 1,4-diaminocyclohexane, 1,6-diaminohexane,diethylenediamine, triethylenetetramine or isophoronediamine. It is ofcourse also possible to use organic compounds which carry differentfunctional groups.

[0039] Examples of suitable solvents are alcohols, preferably loweraliphatic alcohols, such as methanol, ethanol, 1-propanol, isopropanoland 1-butanol, ketones, preferably lower dialkyl ketones such as acetoneand methyl isobutyl ketone, ethers, preferably lower dialkyl ethers,such as diethyl ether, dibutyl ether and THF, isopropoxyethanol,aromatic hydrocarbons, such as toluene and xylene, esters, such as ethylacetate, butoxyethanol, chlorinated hydrocarbons, such as chloroform,sulfoxides, sulfones, amides, such as dimethylformamide anddimethylacetamide, and mixtures thereof In principle it is not necessaryto use a solvent, especially when the hydrolysis of the hydrolysablesilanes leads to the formation of alcohols, such as those mentionedabove. Even in that case, however, it is of course possible to use asolvent.

[0040] With regard to the selection of the solvent it should be ensuredthat the silver compound or silver complex compound present in thecoating composition is preferably soluble in the solvent. For thisreason it is often advantageous to use as solvent a solvent or solventmixture which comprises water or another polar solvent, such as a C₁-C₄alcohol, for example methanol, ethanol, n-propanol, isopropanol,isobutanol or n-butanol or acetone. The silver complex compound mayfirst be formed in a solvent and added as a solution to the coatingcomposition, which may also comprise another solvent.

[0041] The hydrolysable compounds are hydrolysed or (pre)condensed inparticular by the sol-gel method. The sol-gel method is a methodfamiliar to the person skilled in the art. The hydrolysis orcondensation is conducted either in the absence of a solvent or,preferably, in an aqueous or aqueous/organic reaction medium, whereappropriate in the presence of an acidic or basic condensation catalystsuch as HCl, HNO₃ or NH₃. Partial hydrolysis or (poly)condensation ofthe hydrolysable compounds (precondensate) is obtained. The degree ofcondensation, like the viscosity, can be adjusted appropriately, bymeans of the solvent, for example. The liquid sol obtained in this wayis used to prepare the coating composition. The silver compound, in theform for example of the complex compound, and the other components maythen be added. Naturally, the silver compounds, the complexing agent andthe other components may also be added, in any order, prior to thehydrolysis or condensation.

[0042] The coating composition can be applied to the surface of thearticle in any customary manner. Any common wet-chemical coating methodsmay be used. Examples are centrifugal coating, (electro-)dip coating,knife coating, spraying, squirting, spinning, drawing, spincoating,pouring, rolling, brushing, flow coating, film casting, blade casting,slotcoating, meniscus coating, curtain coating, roller application orcustomary printing methods, such as screen printing or flexographicprinting. The amount of coating composition applied is chosen so as togive the desired coat thickness. Work is carried out, for example, so asto give dry coat thicknesses in the range from 1 to 15 μm and preferablyfrom 2 to 5 μm. An advantage in the case of the present invention isthat the coat thicknesses can be chosen very variably.

[0043] Application of the coating composition to the article is followedwhere appropriate by drying, for example at ambient temperature (below40° C.).

[0044] The optionally predried coating is subjected to treatment withheat and/or radiation, in the course of which the silver colloids areformed. It has been found that by virtue of the coating composition usedin accordance with the invention the silver colloids are surprisinglyformed from the silver compounds even at low temperatures. The treatmentmay either be a heat treatment or an irradiation. In one preferredembodiment there is a combined treatment with heat and radiation.

[0045] The formation of the silver colloids takes place in particular attemperatures of below 200° C., especially below 130° C., below 100° C.,and even as low as below 80° C. With heat treatment alone, for example,the silver colloids are formed in the range from 50 to 100° C.,preferably from 60 to 80° C. or 70 to 80° C. The silver colloids mayalso be formed photochemically at ambient temperature by irradiationonly. Irradiation is carried out using actinic radiation, for example UVor laser radiation or electron beams, in order to form the silvercolloids. For irradiation it is particularly preferred to use UVradiation.

[0046] Preferably, irradiation is carried out at the same time as heattreatment. In this case the irradiation, in particular TV irradiation,takes place at a temperature of from 50 to 100° C., in particular from60 to 80° C. This combined treatment takes place, for example, over aperiod of 2-20 minutes. In the case of the corresponding treatmentwithout irradiation, the period of treatment is prolonged by a factor of1.2-2.

[0047] It is particularly important that the colloids generated arerelatively large, for example with diameters of 5-50 nm, 5-30 nm or 5-20nm, and in particular 10-20 nm, since these result in a high long-termactivity. Surprisingly it has been found that, by means of the UVradiation and heat treatment, silver colloids having a diameter of, forexample, 10 to 50 nm or 10 to 30 nm are formed particularly rapidly,even if the silver is added to the composition in the form of a silverdiamine complex. Without UV irradiation, the heat treatment producessmaller Ag colloids (e.g. 5-20 nm). The silver colloids are formed, soto speak, in situ in the applied coating, accompanied where appropriateby the first (further) condensation and crosslinking reaction as thecoating begins to cure.

[0048] The amount of silver compound used in the coating compositiondepends on the desired concentration of silver colloids.

[0049] Curing of the coating composition to give the silver colloidcoating may take place at temperatures below 300° C., preferably notmore than 200° C. and in particular not more than 130° C. Curing ispreferably effected simply by continuing the heat treatment for theformation of silver colloids, i.e., for instance, at temperatures below100° C. or below 80° C., for example at temperatures of from 50 to 100°C. or 60 to 80° C. The duration of curing may be several hours, forexample more than 2 hours, or more. Naturally, the time is shortened ifthe temperature is raised. Formation of the silver colloids at lowtemperatures makes it possible advantageously to prevent rapid curing ofthe coating, which takes place at the relatively high temperaturesotherwise required, so that the colloids are given time to form.Furthermore, initial condensation processes and/or crosslinkingreactions take place in the coating as early as during the heattreatment to form the colloids, leading to an increased viscosity whichcontributes to the stabilization of the silver colloids. Whereappropriate, photochemical curing is also possible.

[0050] The coating obtained comprises an organically modified inorganicmatrix: in other words, in addition to the inorganic matrix framework,there are organic side groups, which may have undergone crosslinkingwith one another or by way of organic compounds, or there may be otherorganic constituents. By increasing the temperature it is possible toreduce the organic fraction.

[0051] By virtue of the method of the invention it is possible, then, toprepare coating compositions which as yet contain no silver colloids, touse these compositions to coat substrates, especially plasticsubstrates, and, by treatment with heat and/or radiation, to preparesilver colloids of the desired size and in the desired concentration ofseveral % by weight. For example, from 0.1 to 40% by weight and inparticular from 1 to 10% by weight of silver colloids may be present inthe finished coating. The coating can be obtained at low temperatures,so that even temperature-sensitive substrates, for exampletemperature-sensitive plastics, may readily be coated with it. Moreover,the coatings display very good elasticity, so that even flexiblesubstrates which readily undergo (reversible) deformation under pressurecan be coated.

[0052] The coated articles of the invention exhibit a strongly biocidaleffect even over prolonged periods of time, especially in contact withliquid media. This produces, in particular, microbicidal coatings onvarious substrates in contact with solutions, with an activity ofseveral months. It has been found that the use of such coatings onmedicine vials which come into contact with the eyes or nose preventsany bacterial contamination.

[0053] The articles coated in accordance with the invention aretherefore particularly suitable for purposes of disinfection,preservation, cosmetic, pharmaceutical or medical purposes. Articlesfrom the pharmaceutical or medical sector, especially containers forpharmaceuticals or articles or components which come into contact withthe human body and are required to be free from germs, are preferredfields of application.

[0054] The examples which follow illustrate the invention withoutrestricting it.

EXAMPLE 1 Production of a Bactericidally Coated Substrate with ThermalCuring

[0055] a) Synthesis of the silver complex solution:

[0056] 0.28 g of silver nitrate is dissolved in 30 g of ethanol (96%).After 30 minutes of stirring, 13 g of isopropanol and 4 g of acetone areadded and stirring is continued for 15 minutes. To form the complex, 1.7g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane are added slowlydropwise with vigorous stirring.

[0057] b) Synthesis of the coating composition:

[0058] 0.03 mol of 3-glycidyloxypropyltrimethoxysilane (GPTMS) (7.09 g)is prehydrolysed with 4.05 g of 0.01 N nitric acid at room temperaturefor two hours. 0.07 mol ofdihydro-3-[3-(triethoxysilyl)propyl]-2,5-furandione (GF20) is introducedas an initial charge and 0.07 mol of 3-aminopropyltrimethoxysilane(APTMS) is added slowly dropwise with ice cooling and vigorous stirring.The mixture is then diluted with 33.9 g of isopropoxyethanol (IPE) andstirred at room temperature for 30 minutes. 18.90 g of 0.01 N nitricacid are added and the mixture is stirred at room temperature for 15minutes. It is then diluted with 43.3 g of IPE and the GPTMSprehydrolysate is incorporated by stirring. After 15 minutes ofstirring, 28.38 g of the silver complex solution prepared in a) areadded and stirring is continued at room temperature for 15 minutes.

[0059] c) Application and treatment:

[0060] Application to the substrate may take place, for example, bydipping, flooding or spinning. The coats are cured at 130° C. for onehour on glass and at 80° C. for 6 hours on PE.

EXAMPLE 2 Production of a Bactericidally Coated Substrate WithPhotochemically Generated Silver Colloids

[0061] 0.03 mol of 3-glycidyloxypropyltrimethoxysilane (GPTMS) isprehydrolysed with 4.05 g of 0.01 N nitric acid at room temperature fortwo hours. 0.07 mol ofdihydro-3-[3-(triethoxysilyl)propyl]2,5-furandione (GF20) is introducedas an initial charge and 0.07 mol of 3-aminopropyltrimethoxysilane(APTMS) is added slowly dropwise with ice cooling and vigorous string.The mixture is then diluted with 33.9 g of isopropoxyethanol (IPE) andstirred at room temperature for 30 minutes. 18.90 g of 0.01 N nitricacid are added and the mixture is stirred at room temperature for 15minutes. It is then diluted with 43.3 g of IPE and the GPTMSprehydrolysate is incorporated by stirring. After 15 minutes ofstirring, 28.38 g of the silver complex solution prepared in Example 1a)are added and stirring is continued at room temperature for 15 minutes.The application of the coating composition to a substrate may takeplace, for example, by dipping, flooding or spinning. To generate the Agcolloids, the coated substrate is exposed three times in the UV curingstation from Beltron, with both lamps at half-power, and at a speed of0.8 m/min. Following UV exposure, the coats on glass are cured at 130°C. for one hour and those on PE at 80° C. for 6 hours.

EXAMPLE 3 Production of a Bactericidally Coated Substrate Comprising aWater-based System With Photochemically Generated Silver Colloids

[0062] 0.5 mol of 3-glycidyloxypropyltriethoxysilane GPTES (139.21 g) ishydrolysed with 1.5 mol of 0.1 N hydrochloric acid (27 g) at roomtemperature for 5 hours. The ethanol formed is stripped off on a rotaryevaporator at 40 mbar with a bath temperature of 35° C. Then 463.0 g ofLevasil® 200 S (silica sol) are incorporated with stirring at roomtemperature for 16 hours. 5 mol % (based on GPTES) ofN-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DIAMO) (5.56 g) areadded slowly dropwise with vigorous stirring and incorporated withstirring for one hour. 326.7 g (0.05 mol of Ag) of the silver complexsolution prepared in Example 1a) are added to the sol and incorporatedwith string for 30 minutes. The silver-containing sol is then filteredthrough a 5 μm filter. The application of the coating composition to asubstrate may take place, for example, by dipping, flooding or spinning.To generate the silver colloids, the coated substrates are exposed threetimes in the UV curing station (type 60/II) from Beltron, with bothlamps at half-power, and at a belt speed of 3 m/min. The exposed coats(on steel or aluminum, for example) are cured at 130° C. for four hours.

We claim:
 1. A microbicidally coated article, especially a container,characterized in that on at least part of the article there is a coatingcomprising an organically modified inorganic matrix comprising silvercolloids which is obtainable by application of a coating compositioncomprising a) a hydrolysate or condensate based on at least onehydrolysable silane with at least one non-hydrolysable substituent andb) a silver compound to the surface of the article and treatment withheat and/or radiation to form the silver colloid coating.
 2. Amicrobicidally coated article according to claim 1, characterized inthat the article at least on the coated parts has a plastics surface oris composed of plastic.
 3. A microbicidally coated article according toclaim 1 or 2, characterized in that the silver compound is a silvercomplex compound, in particular a silver diamine complex compound.
 4. Amicrobicidally coated article according to claim 3, characterized inthat the silver compound is a silver complex compound with2-aminoethyl-3-aminopropyltrimethoxysilane,2-aminoethyl-3-aminopropyltriethoxysilane,aminohexyl-3-aminopropyltriethoxysilane oraminohexyl-3-aminopropyltrimethoxysilane.
 5. A microbicidally coatedarticle according to one of claims 1 to 4, characterized in that thecoating composition is a hydrolysate or condensate based on one or moresilanes of the general formula (I): R_(a)SiX_((4-a))  (I) in which theradicals R are identical or different and represent non-hydrolysablegroups, the radicals X are identical or different and denotehydrolysable groups or hydroxyl groups, and a has the value 1, 2 or 3.6. A microbicidally coated article according to one of claims 1 to 5,characterized in that the coating composition comprises a hydrolysate orcondensate based on a) at least one hydrolysable silane having one ormore epoxide groups on at least one non-hydrolysable substituent, b) atleast one hydrolysable silane having one or more amino groups on atleast one non-hydrolysable substituent, and c) at least one hydrolysablesilane having one or more acid anhydride groups on at least onenon-hydrolysable substituent.
 7. A method of producing a microbicidallycoated article having a silver colloid coating comprising an organicallymodified inorganic matrix, wherein a coating composition comprising a) ahydrolysate or condensate based on at least one hydrolysable silane withat least one non-hydrolysable substituent and b) a silver compound isapplied to at least part of the surface of the article and is treatedwith heat and/or radiation to form the silver colloid coating.
 8. Amethod according to claim 7, characterized in that the treatment isconducted at a temperature below 200° C., in particular not more than130° C.
 9. A method according to claim 7 or 8, characterized in that thesilver colloids are obtained by UV irradiation and/or heat treatment attemperatures from 50 to 100° C.
 10. Use of a microbicidally coatedarticle according to one of claims 1 to 6 for purposes of disinfection,preservation, cosmetic, pharmaceutical or medical purposes.
 11. Use of amicrobicidally coated article according to claim 10 for the keeping ofsolids or liquids, especially pharmaceuticals.